1. Field of the Invention
The present invention relates to a condenser microphone structure, and more particularly to a condenser microphone structure to be assembled in a cellular phone with high frequency noises reduced to as a small level as possible.
2. Description of the Related Art
As such a conventional condenser microphone structure assembled in a cellular phone to enable communications with other cellular phones, there has so far been proposed and developed a wide variety of condenser microphone structures which are known as being small in size and as having one or more terminal connecters electrically connected with parts or elements forming part of the cellular phone.
One of the typical examples of the condenser microphone structures thus known is shown in FIGS. 10 and 11 as comprising a housing 51, a condenser microphone 52 accommodated in the housing 51, an insulator 53 made of a synthetic resin material and also accommodated in the housing 51, and a pair of terminal connecters 54 and 55 securely mounted on the insulator 53. In FIGS. 10 and 11, illustrated is part of a cellular phone 50 which comprises a printed circuit board 56 and a pair of board terminals 57 and 58 securely mounted on the printed circuit board 56 to be electrically connected with elements or parts constituting the cellular phone 50. Each of the terminal connecters 54 and 55 has two projected portions one of which is projected into engagement with the condenser microphone 52 and the other of which is projected into engagement with the board terminals 57 and 58 of the printed circuit board 56. The insulator 53 and the terminal connecters 54 and 55 are integrally coupled with each other and received in the housing 51 in such a way that the terminal connecters 54 and 55 are held in resilient and firm engagement with the condenser microphone 52 and the board terminals 57 and 58 of the printed circuit board 56 to ensure electric connection between the condenser microphone 52 and the printed circuit board 56.
Each of the terminal connecters 54 and 55 is made of a metal plate material having a resilient characteristic and is produced through the steps of firstly punching a metal plate material and secondly bending the punched metal plate material to have respective free end portions bent as will seen from FIGS. 10 and 11.
The conventional condenser microphone structure thus constructed is operated to generate a sound signal with the condenser microphone serving to transform a voice sound into the sound signal when receiving the voice sound from the exterior of the cellular phone.
The conventional condenser microphone structure, however, encounters such problems that the condenser microphone tends to receive high frequency noises through the terminal connecters other than voice sounds, resulting from the fact that the terminal connecters each made of a metal plate material has a relatively large surface area. In addition, the conventional condenser microphone structure is produced through the steps of punching a sheet metal, and bending the punched sheet metal by a metal mold high in precision to produce a terminal connecter in the form of a plate having a uniformed shape as required by customers. The metal mold high in precision needed for production of the conventional microphone structure leads to the fact that the metal mold inevitably becomes at a markedly high production price and needs a relatively long production period for producing the metal mold and punching and bending a sheet metal. In the case of the metal mold low in precision, on the other hand, unstable electric connections are liable to be caused between the terminal connecters and the board terminals and between the terminal connecters and the condenser microphone when the terminal connecters terminal connecters are assembled with the insulator and the condenser microphone.